Stitch-forming mechanism for sewing-machines



1. n. MOFFATT; STITCH FORMING MECHANISM FOR SEWING MACHINE S. APPLICATION FILE'D'IUNE I8. 1918. 374 21 6y Patented Apr. 12, 1921.

5 SHEETS-SHEET 1.

I J. R. MOFFATT. STITCH FORIVHNG MECHANISM/FOR SEWING MACHINES- APPUCATJON FILED JU NE 18. 1913.

1 74,216. Patented P T- 1921? 5 SHEETS-SHEET 2.

Witness v M M f mm 1 W tlttmneg S J. n. MOFFATT. ;sn-Tcn .ronmme MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JUNEIBr I SISL 374 21 Patented Apr. 12, 1921.

5 SHEETS-SHEET 3.

J. H. MOFFATT.

STITCH FORMING MECHANISM FOR SEWING MACHINES. APPLICATION mm mm: I8, 1918.

1,374,216. Patented- Apr. 12, 1921;

5 SHEETS-SHEET 4r Q 1 1 S G g o L 6' l a Q 1' @M .i w Q m V i "D v N W G Q 3% WM I v I 4 14204-1421 J. R. MYOFFATT.

STITCH FORMING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JUNE 1a. 1918.

1,37%2 l 6. Patented Apr. 12, 1921.

5 SHEETS-SHEET 5- UNlTED STATES PATENT OFFICE.

JAMES R. MOFFATT, OF CHICAGO, ILLINOIS, ASSIGNOR TO UNION SPECIAL MACHINE COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

STITCH-FORMING- MECHANISM FOR ,SEXVING-MACHINES.

Specification of Letters Patent.

Patented Apr. 12, 1921.

- Application filed June 18, 1918. Serial No. 240,586.

To all whom it may concern:

Be it known that I, JAMES R. MOFFATT, a citizen of the United States, residing at Chicago, in the county of Cook, State of Illinois, have invented certain new and useful Improvements in Stitch-Forming Mechanism for Sewing-Machines, of which the following is a description, reference being had to the accompanying drawing and to the figures of reference marked thereon.

The invention relates to new and useful improvements in stitch forming mechanism for sewing machines, and more particularly to the shaping of the looper and the arrangement of the looper relative to the needles for forming the well known vamper stitch.

l-ieretofore, in making the vamper stitch, it has been the common practice to use a looper having a hump which draws both needle loops laterally during the back stroke of the looper, so as to open the thread triangle to permit both needles to enter the triangle in front of both needle loops. It has also been the common practice to accomplish this result by forming the looper with a notch and using, in connection with the looper, a stationary retainer secured to the under side of the throat plate.

An object of the present invention is to provide an arrangement of looper and me dles relative to the feed of the material, so that all retainers are done away with and a smooth looper body, free from projections or notches, may be used and at the same time accomplish the spreading of the thread triangle, so as to insure that both needles may enter the triangle ahead of both needle loops. 7

A further object of the invention is to provide a stitching mechanism of the above character, wherein the needles are arranged diagonally of the line of feed, thus staggering the needles so as to minimize the chances of both needles breaking the leather when the stitching mechanism is used in stitching the vamp of a shoe.

A still further object of the invention is to provide a needle guard for positioning the needles in said line diagonal of the feed, so as to insure that the looper will pass both needles without striking the same.

These and other objects will in part be obvious and will in part be hereinafter more fully described.

In the drawings which show by way of illustration one embodiment of the invenlon, I

Figure l is a front view of a sewing machlne embodying my improvements;

F 1g. 2 is a longitudinal sectional view through the work support of the machine, and showing the needles and loopers in front elevation;

Fig. 3 is a transverse sectional view substantially on the line of feed;

Fig. 4 is a plan view of the parts beneath the work support, also showing the position of the needles; I

Fig. 5 is a detail, partly in section and partly in plan, showing the looper support lng shaft and the means for oscillating the same to give the loopers their needleavoidlnrx movement; ig. 6 is a view, partly in plan and partly in section, showing the position of the needles and the loopers as the loopers are m0ving forward and just about to enter their respective needle loops;

Fig. 7 is a view, partly in section and partly in front elevation, of the needles and loopers and the throat plate with the needles positioned as in Fig. 6; I

, Fig. 8 is a view similar to Fig. 6, but showing the loopers at the forward end of their stroke;

Fig. 9 is, a View similar to Fig. 7, but showing the loopers as in Fig. 8;

Fig. 10 is a view similar to Fig. 6, but showing the loopers as having moved laterally and the thread triangle spread and the pairs of needles entering their respective triangles;

Fig. 11 is a viewsimilar to Fig. 7, but showing the loopers in a position as in Fig. 10;

Fig. 12 is a detail in plan of the needle guard operating mechanism.

As above noted, my invention is especially directed to a stitch forming mechanism which is adapted to form a vamper stitch. This vamper stitch is formed from two parallel rows of needle thread loops and a single looper thread, the looper thread loop entering both needle loops at' ach stitch and passing around both needle loops of the next succeedin stitch, whereby it is locked or anchored. 11 order to form this stitch, it is essential that both needles shall enter the thread triangle formed by the looper thread, the body of the looper and the needle thread loops in advance of both needle thread loops. This necessitates the drawing of both needle thread loops to one side or rearwardly in order to spread the triangle andposition the needle thread loops so that both needles may enter, as stated.

Prior to my invention, this has been'accomplished .by providing the looper with a hump on its lower face which operated in th retracting movement of the looper to draw both needle loops to one side and thus spread the triangle. This looper is expensive to make, as it must be made with considerable accuracy in order to accomplish the desired result; and, furthermore, the hump on the looper causes more orless wear upon the threads. This drawing back of the needle thread loops has also been accomplished by meansv of a retainer and a specially constructed looper, but this also is an expensive construction to manufacture and requires great nicety of adjustment in order to accomplish the desired results. The pres ent invention does away with all special shaping of the looper and all retainers, and consists broadly in theuse of a looperwhich is smooth and uniform in cross section throughout. The looper is set so as to move in a line diagonal of the line of feed, so that, as the feed of the fabric carries the needle thread loops of the previously formed stitch rearwardly, the pull of the looper on the needle thread loops as it moves laterally and rearwardly will cause the needle thread loops to slide back on the looper, and thus position'both. of the needle thread loops so that the needles will with certainty enter the thread triangle in advance of said needle thread loops.

The invention further contemplates the setting of the needles in a line diagonal of the lineof feed, so that the looper may readily move into the needle loops. In order to properly position the needles a needle guard is used which makes contact with the needles at the faces thereof passed by the looper as it moves forward into the needle loops and insures that the needles will be positioned, so that the looper will not strike the same.

Referring more in detail to the drawings, 1 have shown my invention as applied to a sewing machine having a work support 1, an overhanging arm 2, in which reciprocates a needle bar 3, carrying, as herein shown, two pairs of. needles 4l-4 and 55. The needle bar is reciprocated by a needlelever 6, whiohis connected to the needle bar by a main link 7 The material is held on the work support 1 by a presser foot 8 and is fed across the work support by a feed dog 9. The feed. dog is carried by a feed bar 10, which is attached to a feed rocker 11; As this feed rockermoves back and forth it causes the feed dog to move back and forth and thus feeding the material to and from the stitching mechanism. The feed bar is raised and lowered b an eccentric 12 on the shaft 13. Jooperating. with the needles 4- 1, beneath the work support, is a looper 14, and cooperating with the needles 55, beneath the work support, is a looper 15. These loopers 141 and 15 are both mounted on the same looper carrier 16. The looper carrier 16 is pivoted at 17 to a looper supporting shaft 18. This looper supporting shaft 18 is mounted in suitable bearings and is oscillated by a fork 19, cooperating with an eccentric on the main shaft 13. The looper carrier 16 is oscillated on its pivotal support by a link 20, which is connected to the needle looper extension 21 carried by the needle looper 6.

It will be noted that the needles ll are arranged in a line diagonal of the line of feed. As herein shown, this line makes an angle of substantially forty-five degrees with the line of feed. The needles 5-5 are similarly arranged in a line diagonal of the line of feed and parallel with the line containing the needles 14. The loopers are similar in construction, so far as the shaping of the body portion of the loopers is concerned. Each looper is uniform in cross section throughout, is free from projections or notches and is substantially concentric with the pivotal axis ofthe looper carrier. Each looper is a thread carrying looper. The loopers move forward into their respective pairs of needle loops at the rear of the needles, as clearly shown in Figs. 6 to 11 of the drawings. In Figs. 6 and 7, I have shown the relative position of the needles and loopers just as the loopers are moving forward for the purpose of entering the needle thread loops. In Figs. 8 and 9 of the drawings, I have shown the loopers as having entered the needle loops and at the extreme forward end of their strokes. .ikftfii the loopers reach the forward end of their strokes, they are moved laterally for the so-called needle avoiding movement. This is accomplished by theoscillating. of the looper supporting shaft. In Figs. and 11 of the drawings, T have shown the loopers as having completed their lateral movement. As the loopers move laterally, they are retracted slightly. The loopers move into the needle loops as the needles are moving upwardly. 'When the needles reach substantially the upper end of their stroke, the feed of the material has taken place.

The needle loops are about the loopers and the feed of the fabric drawing on the needle loops pulls the same tightly about the loopers. As the loopers are retracted with the needle loops held taut about the same, they will be carried back with the loopers and thus separated from the looper thread, opening the triangle so as to insure that both needles of each pair will enter their respec tive triangles in advance of the needle loops. The lateral or needle avoiding movement of the looper is in a direction opposed to the direction of feed, and, therefore, as the looper moves laterally and is retracted, it will further draw on the needle thread loops causing the same to slide back on the looper, so that the combined action of the feed of the material, the lateral movement of the looper and the retracting movement of the looper operate to bring about the spreading of the thread triangle.

It will be noted that where the needles ar set diagonally, if the stitching mechanism is used for stitching the vamp of a shoe and close to the edge of the leather, there is very much less liability of both needles cracking or splitting the leather. In order that the needles may be properly alined and set, I have provided a needle guard 22, which has a diagonal face 23 adapted to cooperate with the needles 4-4, and a diagonal face 24 adapted to cooperate with the needles 5--5. This needle guard is mounted on a bar 26 which is moved by an eccentric on the main shaft, so as to bring the faces 23 and 24:, re-

spectively, into contact with the needles if they are in any way bent or deflected and insures that said needles will be set for the looper to properly pass the same without striking the needles. The faces are arranged diagonally to the line of feed to correspond to the setting of the needles. The eccentric, however, operating the needle guards is preferably the eccentric 12 which also raises and lowers the feed bar. The bar 26 carrying the needle guards is provided with brackets 30 secured thereto by suitable screws, and these brackets are each provided with an arm 31, and the arms 31 extend at each side of the eccentric 12 so that the eccentric as it rotates operating upon these arms will move the bar back and forth. The bar 26 is adjustably secured by screws 27 to a supporting arm 28, and this arm 28 is secured to a roc 29 which is freely supported by an arm 33 freely pivoted at 34: on the rod carrying the feed rocker 11. 'This permits the bar carrying the needle guards to move freely back and forth through the action of the eccentric 12 thereon.

It is obvious that minor changes in the details of construction and arrangement of parts may be made without departing from the spirit of the invention as set forth in the appended claims.

Having thus described my invention, what erally as it is retracted, whereby the diag onal face of the looper operates to draw the needle thread loops about the looper to one side so as to insure both needles entering the thread triangle in advance of the needle thread loops.

2. The combination of a feeding mechanism and a stitching mechanism including a pair of needles set in a line diagonal of the line of feed, a single threaded looper cooperating with said needles, said looper being uniform in cross section throughout, means for pivotally supporting the looper, means for moving the looper forward into the needle loops and for retracting the looper, said looper being set in a line diagonal of the line of feed and parallel to the line of the needles, and means for moving the looper laterally in a direction opposed to the feed of the material as it is retracted, whereby the needle thread loops on the looper are drawn to one side, thus spreading the thread triangle so as to insure both needles entering the thread triangle in advance of both needle thread loops.

3. The combination of a feeding mechanism and a stitching mechanism including a pair of needles set diagonally of the line of feed, a threaded looper cooperating with said needles, means for pivotally supporting said threaded looper, means for swinging the looper about its pivot for causing the looper to enter the needle loops and be retracted therefrom, said looper being smooth on its under face and free from projections and set so as to move in a line diagonal to the line of feed and substantially parallel with the line of the needles when entering the needle thread loops, and means for moving the looper laterally as it is retracted and in a direction opposed to the feed of the fabric, whereby the needle thread loops on the looper are drawn to one side and the thread triangle thus spread, so as to insure both needles entering said thread triangle in advance of both needle thread loops.

4. The combination of a feeding mechanism and a stitching mechanism including a pair of needles set in a line diagonal of the line of feed, a threaded looper mounted to move in a line diagonal to the line of feed and parallel to the line of the needles when entering the needle thread loops, means for 1 moving the loopers laterally, and a needle being held out of the path of the looper as guard having its needle guarding face arit moves forward. 10 I ranged diagonal of the line of feed and par- In testimony whereof, I affix my signaallel with the lines of the needles and disture, in the presence of two witnesses.

posed on the side of the needles passed by JAMES R. MOFFATT.

the looper as it moves forward into the Witnesses:

needle thread loops, and means for moving S. GEORGE TATE,

the needle guard so as to insure the needles OTTO DOHSE. 

